\begin{tikzpicture}[>=Stealth, scale=0.8]
    \filldraw [lightgray] (0, 0) circle (2);
    \draw [dashed, thick] (0, 0) circle(2);

    \filldraw [white] (0, 0) circle (1);
    \draw [dashed, thick] (0, 0) circle(1);

    \draw [->] (-3, 0) -- (3, 0) node[anchor=west] {$x$};
    \draw [->] (0, -3) -- (0, 3) node[anchor=east] {$y$};
    \node at (-0.3, -0.3) {$O$};
    \node [fill=white, inner sep=0pt] at (1.2, -0.3) {$2$};
    \node at (2.2, -0.3) {$4$};
\end{tikzpicture}
